A grammatical category or grammatical feature is a property of items within the grammar of a language. Within each category there are two or more possible values, which are normally mutually exclusive. Frequently encountered grammatical categories include:
number, with values such as singular, plural, and sometimes dual, trial, paucal, uncountable or partitive, inclusive or exclusive
gender, with values such as masculine, feminine and neuter
noun classes, which are more general than just gender, and include additional classes like: animated, humane, plants, animals, things, and immaterial for concepts and verbal nouns/actions, sometimes as well shapes
locative relations, which some languages would represent using grammatical cases or tenses, or by adding a possibly agglutinatedlexeme such as a preposition, adjective, or particle.
A given constituent of an expression can normally take only one value in each category. For example, a noun or noun phrase cannot be both singular and plural, since these are both values of the "number" category. It can, however, be both plural and feminine, since these represent different categories. Categories may be described and named with regard to the type of meanings that they are used to express. For example, the category of tense usually expresses the time of occurrence. However, purely grammatical features do not always correspond simply or consistently to elements of meaning, and different authors may take significantly different approaches in their terminology and analysis. For example, the meanings associated with the categories of tense, aspect and mood are often bound up in verb conjugation patterns that do not have separate grammatical elements corresponding to each of the three categories; see Tense–aspect–mood.
Manifestation of categories
Categories may be marked on words by means of inflection. In English, for example, the number of a noun is usually marked by leaving the noun uninflected if it is singular, and by adding the suffix-s if it is plural. On other occasions, a category may not be marked overtly on the item to which it pertains, being manifested only through other grammatical features of the sentence, often by way of grammatical agreement. For example:
In the above, the number of the noun is not marked on the noun itself, but it is reflected in agreement between the noun and verb: singular number triggers is, and plural numberare.
The bird is singing. The birdsare singing.
In this case the number is marked overtly on the noun, and is also reflected by verb agreement. However:
The sheep can run.
In this case the number of the noun is not manifested at all in the surface form of the sentence, and thus ambiguity is introduced. Exponents of grammatical categories often appear in the same position or "slot" in the word. An example of this is the Latin cases, which are all suffixal: rosa, rosae, rosae, rosam, rosā. Categories can also pertain to sentence constituents that are larger than a single word. A phrase often inherits category values from its head word; for example, in the above sentences, the noun phrase the birds inherits plural number from the noun birds. In other cases such values are associated with the way in which the phrase is constructed; for example, in the coordinated noun phrase Tom and Mary, the phrase has plural number, even though both the nouns from which it is built up are singular.
Grammatical category of noun
In traditional structural grammar, grammatical categories are semantic distinctions; this is reflected in a morphological or syntactic paradigm. But in generative grammar, which sees meaning as separate from grammar, they are categories that define the distribution of syntactic elements. For structuralists such as Roman Jakobson grammatical categories were lexemes that were based on binary oppositions of "a single feature of meaning that is equally present in all contexts of use". Another way to define a grammatical category is as a category that expresses meanings from a single conceptual domain, contrasts with other such categories, and is expressed through formally similar expressions. Another definition distinguishes grammatical categories from lexical categories, such that the elements in a grammatical category have a common grammatical meaning – that is, they are part of the language's grammatical structure.
